NOAEM (natural organic anion equilibrium model): a data analysis algorithm for determining functional properties of dissolved organic matter in aqueous environments: Part II. Organic chemical association

Synthetic organic chemicals (SOCs) are known to be associated with dissolved organic matter (DOM), but the mechanism is not fully understood. A data analysis algorithm (NOAEM) is proposed that refines the association to neutral carbon or cavities of DOM. Neutral carbon is estimated by the difference between total dissolved carbon and carbon associated with natural organic anion (NOA; NOAEM:Part I). The algorithm is based on SOC activity differences in combination with carbon normalized Kow values. The combination directly and indirectly incorporates individual properties of the SOC, the ionic composition, ionic strength and pH of the sample, and a lognormal distribution of cavity volumes (parallel distribution to the NOA distribution). A product of the coefficients, concentrations of SOCs, and concentration of neutral carbon provides estimates for the amounts of associated SOCs. Literature data were utilized for preliminary validation of the algorithm. The theoretical equations are proposed and semiempirical constants reported.